Project description:Nat1 (also known as p97/Dap5/Eif4g2) is a ubiquitously expressed cytoplasmic protein that is homologous to the C-terminal two thirds of eukaryotic translation initiation factor 4G (also known as Eif4g1). We previously showed that Nat1-null mouse embryonic stem cells (mESCs) were resistant to differentiation. In the current study, we found that Nat1 and Eif4g1 share many binding proteins, such as Eif3s, Eif4s and ribosomal proteins. However, Nat1 did not bind to Eif4e or poly A binding proteins, which are critical for cap-dependent translation initiation. In contrast, Nat1 binds to Eif2s, Fmr and related proteins, and Prrc2 proteins more preferentially than does Eif4g1. We also found that Nat1-null mESCs possess a status partially similar to ground state, which is established in wild-type mES cells when treated with inhibitors of the ERK and GSK3 signaling pathways. In Nat1-null mESCs, the ERK pathway is suppressed even without inhibitors. Ribosomal profiling revealed that translation of Map3k3 and Sos1 is suppressed in the absence of Nat1. Forced expression of Map3k3 induced differentiation of Nat1-null mESCs. These data collectively showed that Nat1 is involved in translation of proteins that are required for cell differentiation.
Project description:Nat1 (also known as p97/Dap5/Eif4g2) is a ubiquitously expressed cytoplasmic protein that is homologous to the C-terminal two thirds of eukaryotic translation initiation factor 4G (also known as Eif4g1). We previously showed that Nat1-null mouse embryonic stem cells (mESCs) were resistant to differentiation. In the current study, we found that Nat1 and Eif4g1 share many binding proteins, such as Eif3s, Eif4s and ribosomal proteins. However, Nat1 did not bind to Eif4e or poly A binding proteins, which are critical for cap-dependent translation initiation. In contrast, Nat1 binds to Eif2s, Fmr and related proteins, and Prrc2 proteins more preferentially than does Eif4g1. We also found that Nat1-null mESCs possess a status partially similar to ground state, which is established in wild-type mES cells when treated with inhibitors of the ERK and GSK3 signaling pathways. In Nat1-null mESCs, the ERK pathway is suppressed even without inhibitors. Ribosomal profiling revealed that translation of Map3k3 and Sos1 is suppressed in the absence of Nat1. Forced expression of Map3k3 induced differentiation of Nat1-null mESCs. These data collectively showed that Nat1 is involved in translation of proteins that are required for cell differentiation.
Project description:Nat1 (also known as p97/Dap5/Eif4g2) is a ubiquitously expressed cytoplasmic protein that is homologous to the c-terminal two thirds of eukaryotic translation initiation factor 4G (also known as Eif4g1). We previously showed that Nat1-null mouse embryonic stem cells (mESCs) were resistant to differentiation. In the current study, we found that NAT1 and eIF4G1 share many binding proteins, such as eIF3, eIF4A and ribosomal proteins. However, NAT1did not bind to eIF4E or poly A binding proteins, which are critical for cap-dependent translation initiation. In contrast, compared to eIF4G1, NAT1 preferentially interacts with eIF2, FMR and related proteins, and especially PRRC2 family members. We also found that Nat1-null mESCs possess a transcriptional profile similar, though not identical, to ground state, which is established in wild-type mES cells when treated with inhibitors of the ERK and GSK3 signaling pathways. In Nat1-null mESCs, the ERK pathway is suppressed even without inhibitors. Ribosome profiling revealed that translation of Map3k3 and Sos1 is suppressed in the absence of Nat1. Forced expression of Map3k3 induced differentiation of Nat1-null mESCs. These data collectively showed that Nat1 is involved in translation of proteins that are required for cell differentiation.
Project description:Previous studies have suggested that the loss of the translation initiation factor eIF4G1 homolog NAT1 induces excessive self-renewability of naïve pluripotent stem cells (PSCs). Yet the role of NAT1 in the self-renewal and differentiation of primed PSCs, is still unclear. Here we generated conditional knockout of NAT1 in primed PSCs and used the cells for the functional analyses of NAT1. Our results showed that NAT1 is required for the self-renewal and neural differentiation of primed PSCs. In contrast, NAT1 deficiency in naïve pluripotency attenuated the differentiation to all cell types. We also found that NAT1 is involved in efficient protein expression of an RNA uridyltransferase TUT7. TUT7 is involved in the neural differentiation of primed PSCs via the regulation of human endogenous retrovirus accumulation. These data demonstrated the essential roles of NAT1 and TUT7 in the precise transition of stem cell fate.
Project description:Protein kinase signalling is a major mechanism by which embryonic stem cell pluripotency and differentiation is controlled. However, the pathways and components that regulate embryonic stem cell identity have not been systematically defined. Here, we employ FGF4 signalling as a model system to investigate phosphoproteome dynamics in differentiating mouse embryonic stem cells. We report identification and quantitation of more than 10,000 phosphopeptides, of which hundreds of phosphophoylation sites are regulated more than 2-fold by acute FGF4 stimulation. We hypothesise that phosphorylation sites in this dataset are relevant for regulating the transition of mouse embryonic stem cells from pluripotency towards lineage specific differentiation.
